With the newly stocked, battery-powered S1 and the AC-powered S1A, Interfit joins the small but growing number of manufacturers producing TTL studio strobes. Both flash heads have fast 3-second recycling time at full power and a fraction of that time at lower power. Both have 3 shooting modes: wireless TTL for Canon or Nikon, Manual, and High-Speed Sync. With the separate purchase of a dedicated transmitter, wireless TTL works with your S-series head the way you would with your on-camera flash, but wirelessly, at distances up to 328'. The flash heads use in-camera technology to adjust your exposure from 7.8 to 500Ws across a 7-stop range, from 7.8 to 500Ws. You can tweak the exposure in 1/3 stops over a +/- 3 stop range. It's an ideal system for multiple location shooting or on-the-fly photography.
Sometimes, as in close-up work, you want to make all of the decisions yourself. Manual mode gives you traditional control over the entire power range. It's also the key to High-Speed-Sync (HSS) that allows you to overpower the sun and control background brightness by syncing at shutter speeds as fast as 1/8000-second.
The S1 and S1A ship with multi-voltage power supplies, but the AC/DC S1 also includes a 350-full-power-shot-capable lithium-ion battery that fits inside the flash head's housing and charges in 3 hours.